Tool bits, especially twist drills, are frequently manufactured at different lengths, where the relatively shorter lengths are typically associated with bits of relatively smaller diameters or sizes. With twist drills, for example, small diameter drills tend to be somewhat flexible during use so that relatively long ones will have a tendency to wander or break when employed by the typical operator in a hand drill. When chucking a relatively short twist drill, it is often times necessary to hand position its shank to the jaws of the chuck to guard against contact between the tips of the drill flutes as well as to ensure that a sufficient amount of the drill body extends from the jaws of the chuck. Accordingly, there remains a need in the art for an improved drill chuck having an adjustable depth stop to control an amount by which a tool bit is inserted into the drill chuck.